This invention relates to a semiconductor component comprising a power semiconductor device and a protection device for protecting the power semiconductor device against excessive voltages.
EP-A-372820 describes such a prior art semiconductor component which comprises a semiconductor body having first and second major surface with, adjacent the first major surface, a first region of one conductivity type part of which defines an active device area of a power semiconductor device having at least two electrodes and active device regions each forming with the first region a pn junction extending to the first major surface, and a protection device comprising a series-connected array of semiconductor rectifying elements provided on an insulating layer on the first major surface, the protection device being connected between at least two electrodes of the power semiconductor device for causing conduction between the two electrodes when the voltage across the protection device exceeds a predetermined limit.
As described in EP-A-372820, the power semiconductor device may be a vertical power MOSFET of the DMOS type and the protection element is formed in thin-film technology as a series of back-to-back pn junction diodes connected between the drain and the control or gate electrode of the power MOSFET. The protection device acts to clamp the voltage across the power semiconductor device to the total avalanche voltage of the diode chain so that any excessive energy, for example a rapid rise in the voltage at the drain electrode during turn-off of an inductive load, will be dissipated by conduction of the power MOSFET resulting from avalanche conduction of the diode chain.